Abstract: In this study, the vortex-induced vibration characteristics of a wind turbine tower under the influence of the blades are investigated. Firstly, the two-degree-of-freedom vortex-induced vibration simulation model for a column structure is developed based on computational fluid dynamics（CFD） methods, structural dynamics theory, and overset mesh technique. The simulation results of the model is compared with experimental data from domestic and international literature to verify its accuracy and applicability. The model is used to calculate the two-degree-of-freedom vortex-induced vibration of the tower and blades of an NREL 5 MW wind turbine. The results show that the combination of the overset mesh technique and the CFD method avoids the mesh distortion and negative mesh problems caused by the large amplitude of the structure, and achieves high computational accuracy. Compared with the single tower vibration condition, the mutual interference and merging of the tail vortex shedding of the two are obvious after considering the influence of the blades on the tower, resulting in a more complex double-free motion law of the tower. In the approximate speed range of 3 to 11, the maximum transverse amplitude response of the tower is about 10 times that of the single tower case, and the vibration frequency appears to be "locked".